In most fuel supply systems applicable to internal combustion engines, fuel injectors are used to direct fuel pulses into the engine combustion chamber. Combustion of the fuel in the chamber is improved through effective atomization of the fuel spray and mixing of the fuel and air. One way of achieving increased atomization and mixing is to increase the pressure of the fuel being injected. However, the increased injection pressure capability requires a fuel system to be more robust to operate reliably and safely at the increased pressures thereby undesirably resulting in additional costs.
Another manner of creating increased atomization and fuel/air mixing is to design the nozzle spray holes of the injector to create a turbulent spray pattern. U.S. Pat. No. 5,263,645 issued to Paul et al. discloses a fuel injector nozzle including multiple spray holes formed in a nozzle housing and tangentially oriented relative to a conical interior wall of the nozzle. This spray hole arrangement causes the discharged fuel to swirl and generate a turbulent spray pattern in each hole. However, manufacturing of the spray holes to achieve the tangential positioning is difficult resulting in increased costs.
U.S. Pat. No. 5,029,759 issued to Weber discloses a fuel injector including curved spray holes extending through a nozzle wall. However, the curved spray holes intersect the nozzle cavity interior wall at an angle to ensure smooth, nonturbulent flow through the hole. Also, the spray holes have only a limited angle of curvature.
Consequently, there is a need for a fuel injector including a nozzle assembly having multiple spray holes capable of enhancing fuel atomization and fuel/air mixing.